Low cross-polarization microstrip patch radiator

Abstract

A microstrip patch radiator has parallel conductive strips that are connected at opposite ends by conductive connecting strips and separated by slits. The slits are parallel to the direction of the desired patch currents, and perpendicular to the undesired currents, to provide a low impedance path for currents generating the desired antenna polarization, and a high impedance path for orthogonal currents generating the undesired, cross-polarized radiation of the patch.

What is claimed is:  
     
       1. A low cross-polarization microstrip patch radiator comprising: 
       a plurality of parallel conductive strips each having a first end and a second end opposite said first end, said strips being spaced to form slits parallel to the direction of desired patch currents,  
       a conductive first connecting portion extending transverse to said strips and connecting to each of said first ends of said strips, and  
       a conductive second connecting portion, spaced from said first connecting portion, extending transverse to said strips and connecting to each of said second ends of said strips.  
     
     
       2. The radiator as set forth in  claim 1  including from 4 to 50 of said slits. 
     
     
       3. The radiator as set forth in  claim 1  wherein said first connecting portion, said second connecting portion and said conductive strips have radiator width measured perpendicular to said slits, and 
       said slits have a slit width of from about 0.005 to 0.1 times said radiator width.  
     
     
       4. The radiator as set forth in  claim 1  wherein said first connecting portion, said second connecting portion and said conductive strips form a rectangular shape having a radiator length measured parallel to said slits, and 
       said slits have slit length that is between 0.5 and 0.9 times said radiator length.  
     
     
       5. The radiator as set forth in  claim 1  wherein said first connecting portion, said second connecting portion and said conductive strips form a circular shape having a diameter, with said first and second connecting portions forming portions of an annular band, and 
       said annular has a thickness of between about 0.05 and 0.25 times said diameter.  
     
     
       6. The radiator as set forth in  claim 1  including a microstrip feed connected to said first connecting portion, opposite said strips. 
     
     
       7. The radiator as set forth in  claim 1  including a coaxial feed probe connected to said first connecting portion. 
     
     
       8. The radiator as set forth in  claim 1  wherein said first connecting portion, said second connecting portion and said conductive strips are a single piece of conductive material with said slits being between said strips. 
     
     
       9. A low cross-polarization microstrip patch radiator comprising: 
       a plurality of parallel conductive strips each having a first end and a second end opposite said first end, said strips being spaced to form slits therebetween,  
       a conductive first connecting portion extending transverse to said strips and connecting to each of said first ends of said strips, and  
       a conductive second connecting portion extending transverse to said strips and connecting to each of said second ends of said strips,  
       said first connecting portion, said second connecting portion and said conductive strips forming a rectangular shape, said rectangular shape having a radiator length measured parallel to said slits and a radiator width measured perpendicular to said slits,  
       said plurality of slits including between 4 and 50 slits with each said slit having a slit length that is between 0.5 and 0.9 times said radiator length, and each said slit having a slit width that is between 0.005 and 0.1 times said radiator width.